1. Field of the Invention
This invention relates to strainer devices and, in particular, to devices for removal of unwanted debris and other solid material from fluid-flow streams and the method of removal.
2. Discussion of Related Art
Fluid flow streams often include debris or solid materials carried in the fluid. This can pose a problem for restricted flow passages with respect to plugging and fouling, which is the accumulation of material on the surface of a flow passage. Many industries utilize flow streams and are adversely affected by plugging and fouling problems. As a result, most flow circuits need straining to remove debris and solid materials from a fluid flow. One industry that experiences this problem is the petrochemical processing or petroleum refining industry.
A device commonly used in this industry, as well as other industries, is a heat exchanger that operates by flowing fluid past a heat exchange surface. The surface can be created by bundles of tubes mounted in a shell to effect heat exchange between the fluid stream flowing through the tubes and another fluid that flows within the space between the tubes in the tube bundle and between the tube bundle and the shell. As this type of heat exchanger works well with a large surface area available for heat exchange, the exchangers are designed with a large number of small diameter tubes mounted in a tight bundle and carried in a shell to create a large cumulative heat exchange surface. Debris that flows into a heat exchanger can become trapped at the entrance to the tubes or in between the tubes within a shell. Entrapment of debris leads to excessive pressure drops and “dead zones” where fluid cannot flow. This condition aggravates in-situ fouling and decreases heat-transfer capabilities and efficiencies. This can lead to frequent required cleaning of these devices. Such cleaning can be cumbersome, expensive, and time-consuming. It can also lead to considerable through-put losses.
To strain the fluid and remove solids, a strainer can be used in the flow path. A common strainer device is a bucket strainer. Bucket strainers function by simply screening the fluid flow and collecting the solids in the screen. However, they tend to clog quickly and cleaning is arduous. For example, each bucket strainer can take about two crew days to clean. As a result, the bucket strainers are not cleaned as often as they should be and are not viewed favorably by plant operators.
Since current state-of-the-art strainer devices are cumbersome to maintain, they are not used as often as necessary. This decreases system efficiency and, in the context of a refinery operation, also can add to increased fouling, which is a significant problem in this setting.
There is a need for a device for straining and method of cleaning flow passages that does not require disassembly of the system.